Arrays Utility Class in Java

The Arrays is a utility class which can be found in the  java.util  package. It is very  useful class  and  following  are some of useful methods it has:

• asList(): returns a fixed-size list backed by an array.
• binarySearch(): searches for a specific value in an array. Returns the index of the element if found, or -1 if not found. Note that the array must be sorted first.

               int  indexWhichFound  =  Arrays.binarySearch(arrayToSearch,  keyWhichWantToFind);

• copyOf(): copies a portion of the specified array to a new one. 

               Interger[]   trimmedArray    =   Arrays.copyOf(originalArray, newLength);

• copyOfRange(): copies a specified range of an array to a new one.

                Interger[]   croppedArray    =   Arrays.copyOfRange(originalArray, startLength,  endLength); 

• equals(): compares two arrays to determine if they are equal or not.
• fill(): fills same values to all or some elements in an array.
• sort(): sorts an array into ascending order.

                 void sort(X[] a)
                 void sort(X[] a, int fromIndex, int toIndex)
                 void sort(T[] a, Comparator<? super T> c)
                 void sort(T[] a, int fromIndex, int toIndex, Comparator<? super T> c)

• And other methods you can find in the Arrays class Javadoc.

In addition, the System.arraycopy() is an efficient method for copying elements from one array to another. Remember using this method instead of writing your own procedure because this method is very efficient. Arrays.copyOf(originalArray, newLength)  method  internally  uses that  method .Refer  this  document  for more  about  creating  a  copy  of  array. 

System.arraycopy(Object  copyFromArray, int startingPositionOfArrayToCopy,
                             Object  copyToArray, int landingPositionOfArrayCopy, int totalNumerOfComponentsToBeCopy)

So far I have walked you through a tour of arrays in Java. Here’s the summary for today:

• An array is an object.
• Elements in an array are accessed by index (0-based).
• Advantage of array: very fast access to elements.
• Disadvantage of array: fixed length, not appropriate if a dynamic container is required.
• The java.util.Arrays class provides useful utility methods for working with arrays such as filling, searching and sorting.
• The System.arraycopy() method provides an efficient mechanism for copying elements from one array to another.

 

References Used  :-  Notes about Arrays in Java